Reference techniques for the conventional zero current switch circuit of power-factor correctors used on the present exchange power supply can be found in R.O.C. patent publication Nos. 279514 and R.O.C. patent Nos. I223135. Those techniques mainly aim to reduce conduction switch switching loss of the power-factor correctors (zero switching loss is most preferable) and electromagnetic interference. No. 279514 includes an energy consumption circuit which consists of capacitors, inductors, saturated inductance and resistors to eliminate reverse recovery current and improve electric power factor and electricity utilization efficiency. No. 1223135 proposes an energy conversion circuit which includes an inductor, an energy storing capacitor and a plurality of diodes coupling with a saturated inductor to form a current circuit. It reclaims the reverse energy generated by the power-factor corrector in a reverse recovery condition at different time sequences, and proceeds energy storing and discharging processes to send the reverse energy to a power output end to be reutilized, thereby improves the operation efficiency of the power-factor corrector. However, there are still rooms for improvement in that technique, notably:                1. An inductor L3 has to be added that increases inductor magnetic loss compared with the single saturated inductor originally adopted. The cost is higher.        2. The amount of reverse energy being reclaimed depends on the inductor L3. In the design that involves a heavy loading or high capacity power supply, as the inductor L3 has a constant inductive reactance, the reverse recovery time of the output diode is longer compared with the light loading condition or a lower capacity power supply. As a result, more magnetic loss occurs.        3. The capability of the driving saturated inductor is determined by the amount of discharging current of resistor R1 to capacitor C3. As the discharging time has to be greater than the duty cycle, discharge current cannot be increased. As a result, saturation of the inductor L2 is incomplete, and the loss caused by the resistor R1 increases.        